1. Field of the Invention
The present invention relates to a novel fluorene compound and polymers thereof having a polyphenylene group which can be used as an organic polymer semiconductor and optical electronic material, and especially an electro-luminescence (referred to as xe2x80x98ELxe2x80x99, hereinafter) material, and to an EL element comprising the same.
2. Description of the Background Art
Polyphenylenevinylene (referred to as xe2x80x98PPVxe2x80x99, hereinafter), polythiophene (referred to as xe2x80x98PThxe2x80x99, hereinafter) and polyphenylene group polymers (Synth. Met., 50(1-3), p491 (1992); Adv. Mater, 4, p36 (1992); Adv Mater, 6, p190 (1994); and Chem. Rev, 99, p1747 (1999)) have been widely and representatively known as organic polymer semiconductor and optical electronic materials (refer to Semiconducting Polymers: Chemistry, Physics and Engineering, Edited by G. Hadziioannou and P. F. van Hutten, WILEY-VCH (2000)) or as polymer light-emitting materials (Angew, Chem, Int. Ed., 37, p402 (1998); Nature, 397, p121 (1999); Prog. Polym. Sci., 25, p1089 (2000); and Adv Mater., 12, p1737 (2000)).
Up to now, researches have been conducted on such polymer materials, but these materials have shortcomings that final products are not dissolved in an organic solvent.
PPV or PTh derivatives which emit various lights of blue, green and red having an improved processibility by introducing a suitable substituent thereto have been known (Synth. Met., 62, p35 (1994); Adv. Mater., 4, p36 (1992); and Macromolecules, 28, p7525 (1995)), some of which exhibit an excellent processibility since they are easily dissolved in an organic solvent even though they have a large molecular weight (Adv. Mater., 10, p1340 (1998)).
In addition, fluorene group polymers have lately reported frequently as one of various light-emitting materials (refer to Jpn. J. Appl. Phys., 30, pL1941 (1991); J. Polym. Sci. Polym. Chem. Ed., 31, p2465 (1993); J. Am. Chem. Soc., 118, 7416 (1996); Adv. Mater., 9, p326 (1997); Adv. Mater, 10, p993 (1998); Macromolecules, 32, p1476 (1999); Nature, 405, p661 (2000); Syn. Met., 111-112, p397 (2000); Syn. Met., 122, p79 (2001) and J. Am. Chem. Soc., 123, 946 (2001)).
Besides, there have been known U.S. Pat. Nos. 5,621,131, 5,708,130 and 5,900,327 which disclose fluorene group polymers having a single bond, and U.S. Pat. No. 5,807,974 which disclose a fluorene group alternate copolymer having a conjugate double bond as a light-emitting material for an EL element.
Polymers having an acetylene group have been presented as an organic polymer semiconductor and optical electronic material (refer to Makromol. Chem., 191, p857 (1990); Macromolecules, 27, p562 (1994); J. Chem. Soc., Chem. Commun., p1433 (1995); and Macromolecules, 29, p5157 (1996)), which are mostly related to a nonlinear optical material, a photo conductivity and photoluminescence (hereinafter referred to as xe2x80x98PLxe2x80x99), and Syn. Met, 102, p933 (1999) discloses an example that they are used as an EL material. Researches into other applications have been also reported (refer to Science, 297, p835 (1998)).
Polymers having a diacetylene group have been reported (refer to Prog. Polym. Sci., 20, p943 (1995); CHEMTECH, October, P32 (1993); Macromolecules, 29, p2885 (1996); Syn. Met., 111-112, p429 (2000); and Syn. Met, 119, p105 (2001)). These polymers are as sensitive to heat or light as the acetylene group polymers so that they can easily cross-link, and therefore stable cross-linked polymers can be obtained.
An application of such polymer having an acetylene or diacetylene group as an EL material has been patented to the same applicants of the present invention (U.S. Pat. No. 5,876,864 and Japanese Patent No. 3,046,814). This polymer can be also applied as a nonlinear optical material, a heat resistant polymer, polarized PL polymer, and electric or optical active polymer, as well as a light-emitting material.
Meanwhile, through a Diels-Alder reaction of bis(acetylene), that is, a compound having two ethynyl groups with a compound having a bis(cyclopentadienone) group (refer to J. Org. Chem., 28, p2725 (1963); Chem. Rev., 65, p261 (1965); J. Org. Chem., 30, p3354 (1965); and U.S. Pat. No. 4,400,540), a polyphenylene group polymer in which a plurality of phenyl groups are substituted (refer to J. Polym. Sci., Part B, 4, p791 (1966); J. Polym. Sci., Part A-1, 5, p2721 (1967); J. Polym. Sci., Part B, 7, p519 (1969); Macromolecules, 5, p49 (1972); Macromolecules, 28, p124 (1995); Macromolecules, 33, p3525 (2000)) can be obtained. This polymerization is a reaction that a molecular weight is increased while carbon monoxide is removed. This polymerization is carried out at 100-400xc2x0 C. without a solvent, or with a solvent selected from among toluene, diphenyl ether, o-diclorobenzene and cyclohexylbenzene, by which a polymer is obtained with a high yield of more than 80%. Since several phenyl groups are substituted in the obtained polymer, the polymer is thermally stable and easily dissolved in an organic solvent while has a high molecular weight. Accordingly, such polymer can be applied as a photoreceptor (refer to U.S. Pat. No. 5,882,829), or a dielectric substance in microelectronics industry, and especially, in the field of integrated circuits (refer to U.S. Pat. No. 5,965,679).
In addition, a polyphenylene group polymer can be obtained through an Eidls-Alder polymerization with a bis(xcex1-pyrone) or bis(thiophene dioxide) instead of bis(cyclopentadienone) (refer to J. Chem. Soc. Perkin Trans 1 p355 (1994); and U.S. Pat. Nos. 2,971,944 and 2,890,207).
However, in the case of the aforementioned monomers, that is, the bis(acetylene) compound or bis(cyclopentadienone) compound, preparation cost is high and preparation procedures are difficult, and therefore, various kinds of monomers have not been provided. Especially, in the case of the bis(cyclopentadienone), its kind is so limited that polyphenylene group polymers having various properties and structures can not be prepared.
The inventors of the present invention have made constant efforts to solve the aforementioned problems in the prior art and reached the present invention. That is, the present invention provides a fluorene compound having a polyphenylene group and polymers thereof, prepared from a variety of acetylene compounds and fluorene group bis(cyclopentadienone) monomers, and the use thereof as a light-emitting material.
Therefore, an object of the present invention is to provide a variety of acetylene compounds and fluorene compounds having one or more cyclopentadienone groups.
Another object of the present invention is to provide a variety of novel fluorene compounds having a polyphenylene group and polymers thereof, prepared from the above acetylene compounds and fluorene compounds having one or more cyclopentadienone groups, in which their structures can be identified, and which can be dissolved in an organic solvent and can be used as an EL material and other optical electronic materials.
Another object of the present invention is to provide an EL element using the fluorene compound or polymer thereof as a light-emitting material.
A fluorene compound and polymers thereof according to the present invention can be represented by the following formula (1): 
In formula (1), R1, R2, R1xe2x80x2 and R2xe2x80x2 are the same with each other or different from each other, and respectively represent a hydrogen atom, C1-C22 aliphatic or cyclo-alkyl, or alkoxy group, or C6-C18 aryl or aryloxy group. More specifically, they may be independently a hydrogen atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, ethylhexyl, heptyl, octyl, isooctyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, docodecyl, cyclopropyl, cyclopentyl, cyclohexyl, methoxy, ethoxy, buthoxy, hexyloxy, methoxyethoxyethyl, methoxyethoxyethoxyethyl, cyanoethyl, carboxymethyl, phenyl, phenoxy, tolyl, benzyl, naphthyl or anthrancene, or a derivative thereof. They also may include an alkyl or aryl derivative containing silicon, tin or germanium, or a halogen atom. Examples of such substituent may include trimethylsilyl, triphenylsilyl, tributyltin, triethylgermanium, and a halogen atom such as iodine, bromine and chlrorine.
In formula (1), Ar1 and Ar2 can be the same with or different from each other, and respectively may represent a hydrogen atom, trimethylsilyl, bromine and/or an alkyl group as in the R1, R2, R1xe2x80x2 and R2xe2x80x2. They mainly represent an aromatic substituent having 6 to 18 carbon atoms, respectively, such as phenyl, naphtyl and derivatives thereof.
In formula (1), Arxe2x80x2 is an aromatic or heterocyclic group such as phenylenyl, naphthalenyl, anthracenyl, fluorenyl, thiopenyl, pyrrolyl, pyridinyl, aryloxadiazolyl, triazolyl, carbazolyl, arylamino, arylsilanyl and derivatives thereof, but not limited thereto. Especially preferable examples of the Arxe2x80x2 include the following substituents: 
R1 and R2 as shown in the structures of Arxe2x80x2 are the same groups as defined above.
In formula (1), m is 0 or an integer of above 1, and n is an integer of above 1.
The fluorene compound and polymers thereof of the present invention include a reaction or polymerization product (homopolymer) between the same fluorene compounds of the present invention, a reaction or polymerization product (copolymer) between fluorene compounds of the present invention which are different from each other, and a reaction or polymerization product between the fluorene compound of the present invention and other organic compound.
The kinds of the compounds and polymers thereof in accordance with the present invention are not specially limited, and any compounds and polymers thereof can be used so long as it can be easily prepared and has excellent EL properties.
The fluorene compound in accordance with the present invention can be prepared by a method as shown in the following reaction schemes 1 to 3: 
The fluorene group polymer in accordance with the present invention can be prepared through Diels-Alder reaction between a compound having one or more cyclopentadienone group and a compound having one or more acetylene group, as shown in the following reaction schemes 4 to 12: 
However, with respect to preparation method of the fluorene compounds and/or polymers thereof, besides the above-described method, if a final product has the same structure, any of known methods can be applied. That is, in preparation of the fluorene compounds and/or polymers thereof of the present invention, a solvent, a reaction temperature, a reaction concentration or catalyst, or the like, may not be specifically limited, and likewise the preparation yield.
The organic and polymer group EL element and/or other optical devices of the present invention are fabricated with the fluorene compound and polymers thereof having diverse structures as shown in the Reaction Schemes 1 through 12, especially having a structure of polyphenylene, as a core material.
The fluorene compounds and/or polymers thereof of the present invention can be directly used as an EL material by which they are made into a thin film by a know method such as vacuum-deposition, a spin-coating, a roll-coating, a bar-coating, an ink jet-coating or the like.
In a construction of the EL element, the present invention include not only a typical method in which a light-emitting layer material is inserted between an anode and a cathode, thereby to construct a typical type of an element of anode/light-emitting layer/cathode, but also a method in which both a hole transport layer and an electron transport layer material are used, thereby to construct a type of anode/hole transport layer/light-emitting layer/electron transport layer/cathode. There is no limitation on a construction method of an EL element in the present invention.
As an electrode material for an anode, a material in which a metal or metallic oxide such as ITO (indium-tin oxide), gold, copper, tin oxide and zinc oxide, or an organic semiconductor compound such as polypyrrole, polyaniline and polythiopene is coated onto a transparent support substrate such as glass, transparent plastic or quartz, usually at a thickness of 10 nm to 1 xcexcm can be used. As an electrode material for a cathode, a metal such as sodium, magnesium, calcium, aluminum, indium, silver, gold or copper, or alloys thereof can be used.
Examples of a hole transport layer may include polyvinylcarbazole, 2,5-bis(4xe2x80x2-diethylaminophenyl)-1,3,4-oxadiazole or N,Nxe2x80x2-diphenyl-N,Nxe2x80x2-(3-methylphenyl)-1,1xe2x80x2-biphenyl-4,4xe2x80x2-diamine (TPD). Examples of an electron transport layer may include a known compound such as tris(8-hydroxycnolynato)aluminum, 2-(4xe2x80x2-t-butylphenyl)-5-(4xe2x80x3-biphenyl)-1,3,4-oxadiazole or 2,4,7-trinitro-9-florenone. These compounds are coated with a known thin film forming method such as a vacuum-depositing, a spin-coating, a casting or an LB method.
The light-emitting material of the present invention can be used by being blended with a hole transport layer, an electron transport layer, a different kind of polymer according to the present invention or a conventional light-emitting polymer such as a soluble PPV or PTh derivative. That is, polyvinylcarbazole, poly(1,4-hexyloxy-2,5-phenylenevinylene), poly(3-hexylthiopene) or the like and a polymer according to the present invention can be dissolved together in an organic solvent such as chloroform, and then they can be coated by a spin-coating or a casting method as a thin film. Limitation on the concentration is not necessary therefor, but the light-emitting polymer of the present invention can be used in the range of 0.001 to 99 wt. %, and preferably, 0.1 to 50 wt. % to polyvinylcarbazole. The thin film can have a thickness of 5 nm to 5 xcexcm, and preferably, 50 nm to 1 xcexcm.
The light-emitting material according to the present invention can be used by being blended with a polymer that can be dissolved in a general organic solvent and then formed into a thin film in the above-described range of concentration and thickness. Examples of polymers usable for these purpose may include a thermoplastic polymer such as polymethylmetaacrylate, polyacrylate, polystyrene, polycarbonate, polyvinylchloride, polyethylene, polypropylene, polyacrylonitrile, polyvinylpyrrolidone, polyvinylalcohol, polyvinylacetate, polyvinylbutylal, polyvinylamine, polycaprolactone, polyethyleneterephtalate, polybutylene-terephtalate, polyurethane, ABS, polysulfone and polyvinylfluoride, and a commonly used resin such as acetal, polyamide, polyimide, polyester, alkid, urea, furan, nylon, melamine, phenol, silicone and epoxy.